1. Field of the Invention
The present invention relates to a process for the surface modification of polyester material. The present invention also relates to polyester material which has been surface modified.
2. Description of the Prior Art
There have been numerous attempts in the art to modify polyester material, especially polyethylene terephthalate, so that it is more hydrophilic. For example, U.S. Pat. No. 3,619,276 discloses a process for improving the surface characteristics of polyester shaped articles by coating them with a polyester consisting of a polyoxyalkylene glycol, terephthalic acid or its functional derivative and ethylene glycol. A portion of the terephthalic acid or ethylene glycol may be replaced by an additional component such as difunctional carboxylic acids, alkylene glycols and polyfunctional hydroxy compounds. The coating allegedly improves the antistatic, soil resistance, hygroscopic, water-absorbing and moisture permeating properties of the polyester material.
A further attempt to modify polyester material is described in U.S. Pat. No. 3,416,952. As set forth herein, an essentially linear crystallizable shaped polyester article is treated with a water-insoluble crystallizable polymer compound comprising within a single molecule sufficient repeating units identical to those comprising the crystallizable portions of the polyester to co-crystallize with the same and at least one active group from a defined list of groups which serves to modify the surface of the shaped article. It is not essential that the polymer compound be applied to the surface of the shaped article in crystalline form, but can be applied in molten or dissolved form. It is also not essential that the shaped article be in crystalline form when the treating agent is applied to the surface of the polyester material. However, in those instances where neither the polymeric compound nor the shaped articles is in crystalline form, it is necessary for crystallinity to be developed for both subsequent to the treating process.
Other U.S. patents which describe the chemical modification of polyester material are U.S. Pat. Nos. 3,136,665, 3,310,512, 3,625,754, 3,928,230, 4,035,531 and 4,219,625.
Despite the numerous attempts in the art to modify polyester material so as to alter the characteristics thereof, there still exists a need for a surface modified polyester material with improved hydrophilicity and/or a greater reactivity for bonding using commonly known adhesive systems. The present invention is a result of research efforts in response to that need.